Shortly afterwards, the proprietors commenced building another carriage ; but they experienced considerable difficulty and delay in getting the tubes of a suitable quality of metal, and the joints properly constructed; so that it was not until the month of November, 1829, that they brought it out for trial. An elevation of this machine is represented in the following page. As denoted by the scale of feet, it was of small size, being designed to operate as a drag to another vehicle behind. The boilers were four in number, and instead of the tubular rings being circular, they were made elliptical, with compressed sides, so as to get four of them side by side across the carriage. This was done to obtain as large a surface of metal as possible exposed to the heat of the furnace, as, by this arrange ment, nearly 200 tubes, measuring upwards of 400 feet, were enclosed in a space four feet wide, three feet long, and two feet deep, including the furnaces, (which were inside the boilers) besides the flues and ash-holes. The steam from each of the boilers was conducted into one very strong tube above, of an inch and a half in diameter, to supply the engines ; each of the pipes of communication to it being provided with stop-cocks, to cut off the communication of any boiler that might become unserviceable by leakage, without affecting the pressure on the other boilers. The power was applied through the medium of four working cylinders, which might he considered as separate engines, being fitted so as to work independently of each other, although they might more properly be con sidered as pairs, each pair acting upon a distinct crank, (the throws of which were at right angles to each other,) that gave motion to its respective hind wheel, on the principle described at page 454. These cylinders were only a foot long, three inches and a half outside, and two inches and a quarter inside, diameter ; the pistons were metallic, and made a nine-inch stroke. The cylin ders were posited vertically, and vibrated upon trunnions, through which were made the induction and eduction passages, covered by conical valves, forming an external shell to the trunnions, close to their bearings in the plummer boxes.
These engines were arranged at a, in a row across the carriage. The steam, after working the engines, passed through two copper tanks, which heated the water therein to such a temperature above boiling as to melt the soft solder externally upon the vessels, and rendered it necessary to substitute hard solder ; the steam was carried then to the chimney-funnel to escape. At c is a door, which space across the carriage, and also that at d, were for the use of the man who attended to the furnaces and boilers, besides being used as a receptacle for fuel: at the aides, roof, and bottom of this room were plate-iron shutters, to afford constant draughts of air, that the heat might not be insupportable. The engineer sat on the bind seat p, and at e, over t he engines, was a sheet-iron flap, like the ]id of a box, and at f sliding-doors, enabling the engineer to keep his eye upon the working parts, and, by his spanner, and other tools, to rectify, if required, any slight defect that might take place ; his situation likewise per mitting him to give directions to the furnace-man, and to hold communication with the guide, who sits on the box g. At h is the steering apparatus, consisting of an external case, containing a vertical shaft, at whose upper end is fixed a beveled pinion, which is acted upon by a small beveled wheel, fixed into the axis of the double-handled winch i i. By turning these handles, therefore, the shaft is caused to revolve, and to give motion to a gear at the lower extremity, which acts upon a toothed sector I, attached to the fore axle-tree, and thereb7 turns the fore wheels into the required positions. The lower gear, which is contained in a box k, is adapted to increase the force with a reduced motion, so that the guide, who is able to turn the handles i i quickly, operates with great energy upon the toothed sector, and to overcome with facility the most promi nent of ordinary obstacles in the road. This guiding action being administered by a multiplying power, through the complex medium of toothed wheels, was found to be far more effectual and convenient than when a long lever of a more simple form was used ; besides, that the latter was somewhat dangerous to the guide, who was rendered liable to receive severe blows by the motion of the long handle, when the wheels happened to be turned aside by the opposition of stones laying in the road. A t es is a lamp, not only useful for lighting the
road before the carriage, but serving also (as the prow of a vessel to a mariner) to steer by. The chimney-funnel was made double, the space between the external case a and the internal smoke flue o being for a current of air to pre vent the otherwise unpleasant radiation of heat laterally. The fuel preferred was a mixture of coke and wood charcoal, which produced a great heat, and gave but little black smoke. The motion was communicated to the separate axles of the hind wheels by spur gear of two velocities, changeable at pleasure, as the state of the road, or other circumstances, might require ; this gear was enclosed in boxes, shown at h, and the whole machine was placed upon springs, except the guiding apparatus, which was purposely arranged otherwise, as exhibited in the engraving. This carriage was only taken out of the yard (where it was built) three times : on one of these occasions the writer accom panied it three miles, which it performed in twelve minutes; after which a joint of the induction pipe failed, through which the steam escaped into the air instead of entering the cylinders ; this accident, of course, soon brought the carriage to a stop. Eve7 person who witnessed this experiment was perfectly convinced of the feasibility of the scheme, and that nothing was wanting but a little more experience in discovering and remedying the weak points, which practice alone could effect. The patentee was not, however, afforded the oppor tunity of obviating the defects he had discovered in some parts of his arrange ments, from the want of that support which other men of less talent, but more assuming conduct, easily obtained in abundance. One of these defects consisted in crowding the engines and machinery into too small a space, which, while it rendered accurate fitting and repairs difficult, occasioned some parts to be brought into violent collision by the vibrations of the carriage over a stony road. Another great defect (which was about to be altered) consisted in the iron ring or tire of the wheels being only one inch and a half wide ; in consequence of which, the wheels sank into the ground at least twice the depth of others, having tires of double the width : an acclivity was thus constantly formed before the wheels, which they had either to ascend, or to crush down, causing, in either case, a considerable waste of power. Much ground, it may be observed, that will resist compression entirely from a broad wheel, and allow the carriage to roll over it easily, will give way under a narrow wheel, and so raise up a con stant oppostion to its own progress. The chief disadvantages of broad tired wheels consist in their superior weight, and their greater liability to encounter loose atones lying on the road. The narrower a wheel is the better, provided it does not leave an impression on the road ; but as wheels should be made to suit all the various conditions of the road on which the carriage has to travel, a medium between the extremes should be chosen, which is probably about three inches' width of tire to every half ton that a wheel has to bear. It may be further noticed, that in every experiment made with this carriage, those parts which exhibited a defective action could always be traced to an evident cause; and although the remedy was also rendered obvious, it could not always be carried into effect without considerable delay and expense, which, to the capitalist who is ignorant of mechanical combination, was naturally dis couraging. It will, however, be generally found, that those individuals who have had the most experience in undertakings of this kind, have never dis covered, in the obstacles that have hitherto presented themselves, any thing of ' an insuperable nature, as to its ultimate success.